Phthalate plasticizers have long been used to impart pliability to thermoplastics such as polyvinyl chloride (PVC), and other vinyl polymers. The addition of a plasticizer generally causes a reduction in the cohesive intermolecular forces along the polymer chains. The chains can then move more freely relative to one another, and the stiffness of the polymer is reduced. Phthalate plasticizers have been reported by some sources to be a health concern when found in direct contact with bodily fluids. Because they are readily miscible in organic solvents like plasma and saliva, humans have a chance of ingesting or absorbing them during common medical procedures.
There is a need for effective plasticizers for thermoplastics and other polymers, that are not based on or contain phthalate plasticizers.
Blends of epoxidized soybean oil have long been used as a part of a plasticizer blend. U.S. Pat. No. 3,639,318 describes a PVC film plasticized with a blend of di-(2-ethylhexyladipate and epoxidized soybean oil.
U.S. Pat. No. 5,227,417 describes using a blend of phosphate ester based plasticizer, brominated aromatic ester plasticizer, and epoxidized soybean oil.
WO 2010/006101 describes the use of epoxidized methyl soyate as a PVC plasticizer. WO 2009102877 describes a blend of soy methyl ester epoxide blended with epoxidized soybean oil. This blend involves the mixture of components previously epoxidized.
Surprisingly, it has now been found that a plasticizing composition may be formed for thermoplastics and other polymers, by a process that includes forming a blend of one or more fatty acid esters and one or more bio-based oils, then epoxidizing the resulting blend. The resulting epoxidized composition is lower in residual contaminants and detrimental reaction by-products, than a blend made by blending together components that had already been epoxidized separately. Additionally, there are many process advantages of using the process of the invention.